Joule Thief LED Driver


[Bird603568] sent in this sweet little LED hack that’ll drive a white LED from just 1.5 volts. The circuit consists of a pair of coils wound on a ferrite core, a resistor and a NPN transistor. He notes that the circuit still functions even at .35v. The version pictured is even small enough to fit inside a normal flashlight bulb base.

Pulse Soldering Iron


I’m always interested in new ways to solder. [SPman] sent in this diy pulse soldering iron. It heats up in 5 seconds on demand, then cools in about 15. The writeup is a bit terse (since it’s translated from Russian), but it would definitely be handy for larger wiring jobs. The transformer is hand wound, and an oscillation driver forms a sort of crude frequency modulation to run the MOSFETS that drive the heating elements. I’d keep it away from delicate electronics unless you’re confidant of the temperature stability. It was designed for 220V, so you’d need to modify the transformer a bit to get similar performance on a 110V circuit.

Build Your Own Car… From Scratch


Most of us settle for modding the latest car we’ve bought. [Steve Graber] took another approach and built his own car from scratch. [John] sent in this impressive project. The original was built around Toyota MR2 parts and the body was made from fiberglass after the design was hand made from a wooden support frame, foam and drywall mud that was sanded down to create the shape. After that, molds were made from the slug to allow the panels to be cast from fiberglass. [Steve] is actually offering the car up as a build-it-yourself kit. Personally, I’d like the see the price come down a bit – the 1,500lb street weight would make a sweet basis for an electric car.

Bonus: If you’d doing EVs, bots or R/C toys, you might like this comparison of the latest breed of Lithium Iron Phosphate batteries by [Ian Hooper].

$25 Head Mounted Display


[Jake] sent in his source for a cheap head mounted display. In his writeup he notes that the spy video car comes with quite a pile of handy electronics – video tx/rx, camera and this simple black and white monocle head mounted display. (Which happens to be available as a replacement unit for a mere $20) The screen is a Kopin 300M (Black and white, 300×240 pixels) The display is actually somewhat usable out of the box, but he takes the time to note some simple mods that’ll improve the displays performance.

If you ever bought a virtual boy just to gut the display, then you know you want one. In fact, I’ve got a perfect project in mind for this particular toy.

Back From Belize Extra


Yesterday, I was standing on a tropical island off the coast of Belize. Vacation rocked with lots of SCUBA diving, spearfishing and snorkeling. I’m back home, shaking off the jet lag and clearing up my inbox. Thanks to [fabienne] for filling in and letting me unplug for a while!

[Darkrom] has set a new standard for Hack-A-Day readers… I haven’t seen it in person, but that looks like a legit Hack-A-Day tattoo.

[null] sent in a new use for a frequency generator, a spare car amp, a sub-woofer and a plastic coffee can – brass cartridge polishing.

[LoopyMind] sent in this Game Boy Advanced Movie Player IDE hack. It’s pretty much a direct CF to laptop drive cable with an external battery supply.

[Dingolishious] sent in a POE UPS/remote power control solution. Could be handy if you’re using many POE devices, or if you’re having power issues. He added an inexpensive remote power monitor/switch solution behind his UPS. It senses power outages and kicks out an email – and allows remote power cycling of his POE devices. Of course, if you’ve got a linux box behind the UPS, it can monitor the output from the UPS and send notifications.

[William] added a preamp stage to his iKEY usb recorder. looks like an interesting toy – it’ll record audio directly to a USB flash key. The pre-amp allows him to record in more challenging environments.

[Andrew] noted a simple mod to increase the deadly fire power of the ubiquitous airsoft pellet gun. It’s just a matter of reducing some extra space in the spring compression area.

Last but not least, [VIPER] modded his projector to use a 12v halogen headlight bulb. Not a bad idea – at one point I was pondering a 550 watt source four halogen as a possible replacement.

Roasting Pan Audio Amplifier

When you need a rigid, vibration-free chassis for your amplifier, look no further than a roasting pan. I’ve used cast cement for subwoofers, but using a cooking pan bolted to a heavy wooden chopping board is a cheap way to get a rigid surface on which to build audio gear. The amp circuitry used by [Mark] is not complex, but it gets the job done. The “oxygen free copper cable” and “pure silver wire” are not needed, just make sure you have a solid mechanical connection. In other words, just tin your wires, bend small “u” shapes at each end, hook them together, and apply solder to the heated ends. Alternatively, hold the ends of stranded wires parallel to each other and twist the ends together before tinning, then solder. Test everything with a multimeter while moving wire joints to make sure you have no weak connections. Now you won’t waste your money on hyped-up cabling materials.

Thanks to [Gio] (who seems to have some personal audio projects as well) for the tip.

Build Your Own GPS And GLONASS Receiver

[superlopez] sent in this detailed article (mirrored here and here) which describes how to build a GPS and GLONASS (the Russian version of GPS) receiver. The resulting device is gigantic compared to one of those tiny bluetooth USB GPS units, but the ability to build one’s own receiver is one of those post-apocalyptic skills I sure would like to have. The creator of the article [Matjaz Vidmar] aka [S53MV] also has pages on Packet-Radio (PKT) transceiver improvements (PKT gets my vote for the best post-apocalyptic technology, and the only believable technology featured in the Transformers movie), and a more sophisticated homemade frequency counter than the one featured earlier this summer.

In 2005 we featured a from-scratch GPS receiver as well, thought the project site seems to be down. If your GPS unit just needs a better antenna, check out [Will]’s how-to from last year.